A PAYLOAD CONTROL DEVICE
A payload coupler with a position control device for controlling a position of the payload coupler when suspended from a lower end of a line for attachment at an upper end thereof to a lifting device. The payload coupler includes a payload attachment means and at least two propulsors. The payload attachment means couples to and/or decouples from a payload and is arranged to directly couple the payload coupler to a payload. The propulsors are configured to generate resultant propulsion forces which are non-parallel and having at least a component perpendicular to the axis of the line when the line is hanging taut under gravity.
1 . A payload coupler with a position control device for controlling a position of the payload coupler when suspended from a lower end of a line for attachment at an upper end thereof to a lifting device, the payload coupler comprising:
a payload attachment means for coupling to and/or decoupling from a payload, the payload attachment means arranged to directly couple the payload coupler to a payload, and
at least two propulsors,
wherein the at least two propulsors are each configured to generate resultant propulsion forces which are non-parallel, each resultant force having at least a component perpendicular to the axis of the line when the line is hanging taut under gravity.
2 . The payload coupler of claim 1 , wherein the components of the resultant propulsion forces perpendicular to the axis of the line when the line is hanging taut under gravity are orthogonal.
3 . The payload coupler of claim 1 , wherein the propulsors are each selectively operable to generate resultant propulsion forces in two opposite directions.
4 . The payload coupler of claim 1 , wherein the propulsors are first propulsors and the payload coupler further comprises two second propulsors, each second propulsor configured to generate a resultant propulsion force parallel to a resultant force generated by a respective one of the first propulsors, the respective first and second propulsors being spaced apart in a direction perpendicular to their respective resultant force.
5 . The payload coupler of claim 1 , wherein the propulsors are arranged to generate a resultant force perpendicular to the axis of the line when the line is hanging taut under gravity.
6 . The payload coupler of claim 1 , wherein the propulsors are arranged to generate a force having a component parallel to the axis of the line when the line is hanging taut under gravity.
7 . The payload coupler of claim 1 any preceding claim, further comprising a movement sensor and a control system, the control system being coupled to the movement sensor and the propulsors, and
wherein the control system is arranged to drive the propulsors to oppose movement of the device detected by the movement sensor.
8 . The payload coupler of claim 1 , further comprising a position sensor and a control system, the control system being coupled to the position sensor and the propulsors, and
wherein the control system is arranged to drive the propulsors to move the device to a target location.
9 . A lifting system comprising:
a line,
the payload coupler of claim 1 , the payload coupler coupled to the lower end of the line, and
a lifting device coupled to the upper end of the line, the lifting device having a lifting device propulsion means for moving the lifting device.
10 . The lifting system of claim 9 , wherein the lifting device propulsion means is operable independently of the propulsors.
11 . The lifting system of claim 9 , wherein the lifting device comprises a power source arranged to provide power to the payload coupler.
12 . A method of controlling a position of a suspended payload coupler, the method comprising:
providing a payload coupler suspended from a lower end of a line which is coupled at its upper end to a lifting device, the payload coupler having a propulsor configured to generate a resultant propulsion force having at least a component perpendicular to the axis of the line when the line is hanging taut under gravity,
operating the propulsor to generate a propulsive force to maintain the payload coupler in a first stable position or to move the payload coupler along a predetermined path; and
coupling a payload to the payload coupler or decoupling a payload from the payload coupler while the payload coupler is maintained in the first stable position or moved along the predetermined path.
13 . The method of claim 12 , further comprising operating the propulsor to generate a propulsive force in order to move the payload coupler to a second stable position different from the first stable position.
14 . The method of claim 12 , wherein the line is substantially vertical when the payload coupler is in the first stable position and/or the second stable position.
15 . The method of claim 12 , wherein the line is not vertical when the payload coupler is in the first stable position and/or the second stable position.
16 . The method of claim 13 , further comprising coupling the payload to the payload coupler or decoupling the payload from the payload coupler while the payload coupler is in the second stable position.
17 . The method of claim 12 , wherein the payload is coupled to or decoupled from the payload coupler by movement along the predetermined path.
18 . The method of claim 12 , further comprising operating a propulsion device of the lifting device and the propulsor independently.
19 . The method of claim 12 , further comprising increasing or decreasing a tension in the line by operating the propulsor to generate a force with a component in a vertical direction.